Australasian Science: Australia's authority on science since 1938

Gravitational Waves Detected

By AusSMC

Australian astronomers involved in the detection of gravitational waves discuss the significance of the discovery 100 years after Einstein predicted them.

“We built the most massive scientific instruments in the world and made them so sensitive that they approach limits set by quantum mechanics. On September 14 last year they directly detected for the first time the weakest signals in the universe, gravitational waves, generated in the most violent event yet recorded – the collision of two solar mass black holes.

“The energy released in this binary black hole collision was equivalent to 10 billion billion billion times the world’s nuclear arsenal. What’s even more fascinating is that this event did not (and does not) emit electromagnetic waves or neutrinos. The only way to observe it was with space–time change sensors – our giant laser interferometers.

“With this detection we have shifted from the realms of theory to the beginning of a new astronomy. Hopefully this first observation will accelerate the construction of a global network of detectors.”

Professor David McClelland is Director of the Centre for Gravitational Physics at the Australian National University. He is a member of the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA), which contributed to the gravitational waves discovery.

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“The discovery confirms Einstein's prediction that gravitational waves exist, validating one of the pillars of modern physics. It confirms that black holes exist and orbit each other in binary systems, teaching us important lessons about how stars are born and live their lives.

“Einstein's theory of relativity, which predicts the existence of gravitational waves, brings together the concepts of geometry and gravity in a wonderfully inspiring way. The sources that LIGO detects, like black holes, are the home of some of the most fascinating physics in the universe. It is very exciting to think that we now have a new and powerful tool at our disposal to unlock the secrets of all this beautiful physics.

“Gravitational waves are neither scattered nor absorbed by the material they pass through, so they let us peer right into the heart of some of the most extreme environments in the universe, like black holes and neutron stars, to do fundamental physics experiments under conditions that can never be copied in a lab on Earth. The possibilities are endless.”

Professor Andrew Melatos is from the School of Physics at the University of Melbourne, and a member of ACIGA.

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“Gravitational waves are akin to sounds that travel through space at the speed of light. Up to now humanity has been deaf to the universe. Suddenly we know how to listen. The universe has spoken and we have understood!

“We have opened a whole new frontier by creating exquisite and almost unimaginable technologies that have allowed us to measure vibrations as small compared with atoms as atoms are compared to people. By measuring the smallest amount of energy ever measured, we have detected the most powerful explosion ever observed in the universe, in which three times the total mass energy of the sun was emitted in pure explosion of gravitational energy in a time of less than one-tenth of a second.”

Winthrop Professor David Blair is the Director of the Australian International Gravitational Research Centre at the University of Western Australia.

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“The discovery of this gravitational wave suggests that merging black holes are heavier and more numerous than many researchers previously believed. This bodes well for detection of large populations of distant black holes. It will be intriguing to see what other sources of gravitational waves are out there, waiting to be discovered.”

Dr Eric Thrane is from the School of Physics and Astronomy at Monash University, and a member of ACIGA.

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“The detection of gravitational waves by the LIGO consortium is one of the most significant discoveries in physics in the past century - confirming one of the key predictions of Einstein's Theory of General Relativity. Much of the Universe is governed by this famous theory of Einstein's, and with him having published it 100 years ago, 2016 is a great time to prove Einstein right.

“This discovery will also be the beginning of a whole new realm of physics - gravitational wave astrophysics. The gravitational waves that have been detected are likely to have been produced by the merger of two black holes , and that is something we've not been able to see before. The ability of ALIGO to detect gravitational waves from such dramatic events will allow them to be located in the universe and be followed up by telescopes, with any associated radiation providing vital additional information on these enigmatic objects.

“What's also really satisfying for me is the very strong involvement of Australian physicists and astrophysicists in the development of gravitational wave detectors and this very first detection – most notably David Blair's Group at the University of Western Australia and David McClelland's team at the ANU.”

Warrick Couch is President of the Australian Institute of Physics and Director of the Australian Astronomical Observatory.

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“This is an immensely important discovery for physics and astronomy. Back in 1915 Einstein proposed that space–time is a four-dimensional fabric that can be pushed or pulled as objects move through it.

“If you run your hand through a still pool of water, waves will follow in its path, spreading throughout the pool. Now that we've caught these waves, we can use them to see the universe in entirely different ways to what was previously possible.”

Dr Simon Johnston is the Head of Astrophysics at CSIRO, which contributed to the research.